- After severe disturbances
- remove or bury biomass
- no soil or seeds remain
- Glacial retreat, mud-flows, floodplains, lava flows
- Colonization:
- species that handle stresses
- low nutrients / minimal soil
https://www.youtube.com/watch?v=eEvRLAACNz4
https://wps.pearsoncustom.com/wps/media/objects/2128/2179441/28_03.html